As one implementation of high speed optical transmission, an advantage of parallel optical transceiving (e.g., optical signal transmission and reception) lies in technology and cost. Parallel optical transceiving utilizes intermediate, high speed photoelectric technology and repeating (e.g., multiple) channels to achieve a high speed, large capacity transmission. Particularly, in short-distance communication, such as interconnection between backplanes in a large communication system and data transmission within a local area network, parallel optical transceiving is characterized in that it has a high transmission speed, small size, low weight, low crosstalk, etc. Driven by wireless communication, video, voice service, etc., a communication solution of higher speed, larger capacity and longer distance is requested and/or desired.
In conventional parallel optical transceivers, VCSELs (Vertical Cavity Surface Emitting Laser) are used as optical signal sources. As limited by the material(s) and the manufacturing technique(s), VCSELs are suitable for a waveband of 850 nm, but use at other wavelengths or wavebands has met challenges that have been difficult to overcome. Standard fiber transmission at 850 nm brings large loss(es) such that conventional parallel optical transceivers having VCSELs are used primarily for short-distance transmission within a range of about 300-500 meters, far below the requirement for data transmission and PONs (Passive Optical Networks).
Reference 1 (CN1665086A) discloses adding a gradient-index or graded index (GRIN) lens array into a VCSEL array coupled to a fiber array to smoothly and continuously focus emergent rays on the access point of the fiber array. This design is relatively complicated, and appears to be limited to a parallel optical transmitter for a short-distance transmission (less than 300 meters).
Reference 2 (EP1253450A2) discloses a design including three fibers and an optical portion, wherein the optical portion comprises two GRIN lenses and a filter. Specifically, this design relates to wavelength division multiplexing without parallel light waves. Moreover, this optical link design does not appear to be broadly applied or adapted.